The powder for electrode active material is being used as a raw material of a positive electrode active material. The positive electrode active material usually comprises a transition metal element such as Mn. The powder for positive electrode active material includes a powder of an oxide or the like comprising the above-described transition metal element, and this powder and a lithium compound are mixed and calcined, whereby a positive electrode active material is obtained. Such a positive electrode active material is being used as a material of a lithium secondary battery.
A lithium secondary battery having the positive electrode active material above has already been put into commercial use as a small power source for cellular phones, notebook computers and the like. Because of its applicability as a large power source, for example, as a power source for vehicles such as electric vehicle and hybrid electric vehicle or as a power source for distributed power storages, the demand thereof is on the rise. However, in a lithium secondary battery, a large amount of scarce metal elements such as lithium are contained in the raw material of the positive electrode active material, and there is concern about supply of the scarce material to meet the growing demand for a large power source.
In response, a sodium secondary battery is being studied as a secondary battery capable of eliminating the concern about supply (see, for example, Patent Document 1). The sodium secondary battery can be fabricated using a material which has a plentiful supply and which is inexpensive, and its commercial application is expected to allow for large power sources to be supplied in large amounts.
Patent Document 1: Japanese Unexamined Patent Publication No. 2006-216508